User:Paul Rothenberg/Notebook/Pauls Notebook/2013/06/04

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Reaction of OPD+H2O2 with Mb/Tris Catalyst in Isopropanol Suspension

Going to run the same procedure as Friday and yesterday, but with Mb/Tris.

Based on the inconsistencies of the previous reactions, I am going to first take the reference spectrum of OPD and Mb in Isopropanol AFTER centrifuging it. Then, I am going to run the reaction in 20 minute intervals and use fresh pipette tips each time to see if that makes a difference. Also, I'm going to try to use more than 1 mL aliquots of solution to centrifuge, so I can hopefully avoid pulling any of the collected precipitate into the cuvette. I am also going to only remove the sample to be centrifuged right as it needs to be; not isolated from the original reaction as I had done previously.

For the reference solution, I am going to use 6.74 mL of OPD and 0.75 mL of Mb solutions, and what I would have added in as H2O2 will be Isopropanol. Hopefully that will give a better reference spectrum.

9:43 The reaction was started.

12:03 The reaction was stopped at 140 minutes.


Mb Tris OPD H2O2 Isopropanol WORKUP GRAPH.png

Again, even after centrifuging the reference solution and using fresh tips, the data was not consistent. The tris buffered Mb had the most consistent values in aqueous solutions, but in suspension, that was not the case. The reference peak was still the highest in the overall graph, and again, 120 minutes had the highest absorbance, and 40 minutes had the lowest absorbance.

Isopropanol Suspension Comparison

Mb Citrate OPD H2O2 Isopropanol WORKUP GRAPH.png

Mb Phosphate Isopropanol Suspension GRAPH.png

Mb Acetate OPD H2O2 Isopropanol WORKUP GRAPH.png

Mb Tris OPD H2O2 Isopropanol WORKUP GRAPH.png

With the exception of Mb/Citrate, the highest absorbances were at the penultimate timed spectrum. There is also a peak at a little over 650 nm on all of the graphs, and it peaks to the bottom. Not quite sure what this is; it is also seen in the reference spectrum. It could potentially be any solid buildup from centrifugation that was absorbed into all of the spectra.

The OPD/Mb reference always had the highest absorbance (with the exception of Mb/Citrate).